标题：中国北方阿尔山的不冻河

章节概要：

1. 不冻河的位置与现象：介绍中国北方阿尔山冬季河流大多结冰，唯有哈拉哈河上游约20公里长的一段即使在零下30 - 40度也不结冰的现象。
2. 不冻河的成因：解释不冻河的秘密在于河床下有地热活动，热量使河水温度高于冰点，从而不结冰。
3. 不冻河对动物的意义：讲述在严寒冬季，不冻河成为动物的温泉浴场，例如一群牛在河边漫步，迫不及待地涉水享受温暖的河水。

详细内容：

In winter, Arshan, a city in northern China, becomes a world of ice. Its rivers become frozen, all except one. Upstream of the Halhengol River, there is a stretch around 20 kilometers long. Even in winter, when the air temperature typically drops to minus 30 to 40 degrees Celsius, this section remains ice - free. People call it The unfrozen river. Its secret lies deep beneath the river bed, where the river passes over an area of geothermal activity near Arshan. The heat from below raises the temperature, allowing the river water to stay above freezing point, and so it remains ice - free. During the harsh winter, it even becomes a spa for animals. A group of cattle are strolling along the riverbank. They can't wait to wade through the water. Look closely and you'll see steam rising from the surface of the river. Such a nice warm bath. Let's leave the cattle to enjoy it.

总结：这段文字主要讲述了中国北方阿尔山冬季存在不冻河的现象、其形成的原因以及这条不冻河在严寒冬季对动物的意义。